lfts Flashcards
why order LFTs
confirm clinical suspicioun of potential liver injury or disease or to distinguish between hepatocellular injury (hepatic jaundice) and cholestasis (post hepatic or obstructive jaundice
what tests are used to assess liver function
ALT, AST, LP, GGT, bilirubin, albumin and prothrombin time
what tests distinguish between hepatocellular damage and cholestasis
ALT, AST, ALP, GGT
What are bilirubin, albumin and PT used to assess
the livers synthetic function
more than a 10 fold increase in ALT
two arrows
two arrows for ALP
more than a 3 fold increase
when is ALT found
within hepatocytes and enters the blood following hepatocellular injury
when is ALP found
in the liver, bile duct and bone tissues - often raised in liver pathology due to increased synthesis in response to cholestasis as a result
what suggests hepatocellular injury
a greater than 10 fold increase in ALT and less than 3 fold increase in ALP
what suggests cholestasis
a less than 10 fold increase in ALT and more than 3 fold increase in ALP
what is GGT raised suggestive of
biliary epithelial damage and bile flow obstruction
raised ALP and GGT
cholestasis
lone ALP rise
non hepatobiliary pathology
causes of isolated rise in ALP
bony metastases or primary bone tumours, vitamin D defiency, recent bone fractures, renal osteodystrophy
causes of isolated bilirubin rise
gilberts syndrome, haemolysis
how to check the livers synthetic functions
serum bilirubin, serum albumin, prothrombin time, serum blood glucose
normal urine and normal stools
pre hepatic cause
dark urine and normal stools
hepatic cause
dark urine and pale stools
post hepatic cause (obstructive)
causes of conjugated hyperbilirubineamia
hepatocellular injury and cholestasis
causes if unconjugated hyperbiliruvineamia
heamolysis, impaired hepatic uptake, impaired conjugation
what causes dark urine
conjugated bilirubin
what causes pale bulky difficuly to flush stool
obstructive post hepatic pathology
what does albumin do
helps bind water, cations, fatty acids and bilirubin and plays a role in oncotic pressure of the blood
why can albumin fall
liver disease, inflammation, protein losing enteropathies or nephrotic syndrome
what is PT
the measure of the bloods coagulation tendncy specificlly the extrinsic pathway. In the absence of other decondary causes such as anticoagulant drug use and vit K deficiency an increased PT can indicate liver disease and dysfinction. The liver is responsible for the syntheiss of clotting factors therefore hepatic pathology can impair this process resulting in increased prothrombin time
ALT>AST
chronic liver disease
AST>ALT
cirrhosis and acute alcholic hepatitis
common causes of acute hepatocellular injury
poisoning, infection, liver ischaemia
common causes of chronic hepatocellular injury
alcoholic fatty liver disease, non alcoholic fatty liver disease, chronic infection, primary biliary cirrhosis
